I have searched forum and FAQ to see how to sync Rainlendar with iPhone. There are discussions using google calendar. However, I do not use google calendar. I have the calendar that comes with iPhone and Fantastical (paid app). I bought Rainlendar Pro hoping I could sync it with iPhone. The problem is, I don't know how. I am beginner for Rainlendar, and need step by step instruction to sync this with iPhone.
Please help.

Welcome to the forum, leetopia.
I'm not using iPhone, but I think this maybe can help you.
(The following description also can be found in Rainlendar Help File.)

Use Apple iCal
(The Apple iCal is supported only in the Mac version of Rainlendar Pro.)
- Right click on the calendar window and choose Options from the menu.
- Select the "Calendars" page.
- Click the Add... button.
- Choose Mac iCal from the list (if it's not in the list you have the Rainlendar Lite version installed still).
- Select the calendar you want to see in Rainlendar.
- Click next and name your calendar.
- Click finish to close the wizard dialog.
- Click OK to close the options and you should see the events in Rainlendar.

Use iCloud Calendar
(This is supported only in the Pro version of Rainlendar.)
- First you need to find out the principal url for the iCloud CalDAV server. To do this you need to open the Terminal and go to "/Users//Library/Calendars" folder. In the folder find out the name of the folder which ends with .caldav (if the folder is not there you need to first connect your iCal with iCloud). In the *.caldav folder open the Info.plist and check the value of the PrincipalURL property (it should be something like p11-caldav.icloud.com:443//principal/).
- Right click on the calendar window and choose Options from the menu.
- Select the "Calendars" page.
- Click the Add... button.
- Choose CalDAV calendar from the list (if it's not in the list you have the Rainlendar Lite version installed still).
- Enter the PrincipalURL as the URL and your Apple ID user name and password.
- Click the Select Calendar button - Select the calendar you want to see in Rainlendar. - Click next and name your calendar.
- Click finish to close the wizard dialog.
- Click OK to close the options and you should see the events in Rainlendar.